In recent years, use of mobile communications devices for voice telephone services, email or text messaging services and even multi-media services has become commonplace, among mobile professionals and throughout the more general consumer population. Mobile service provided through public cellular or PCS (personal communication service) type networks, particularly for voice telephone service, has become virtually ubiquitous across much of the world. Although networks in different countries often utilize different technologies, increasingly, mobile stations support roaming through many countries or even globally. To support such broad customer roaming, many mobile stations today are capable of using various networks and network technologies in many different countries. A variety of features of the mobile stations depend at least in part on knowledge by the mobile station and/or its user of the particular country in which the mobile station is currently operating.
For example, for a roaming subscriber, there is a financial benefit to the carrier selling service to the subscriber to implement procedures in the subscriber's mobile station to insure that the device selects the system in any area of operation that offers the best financial arrangement for services provided to the carrier's subscribers. A network operator in one country may have different financial roaming agreements with operators in other countries or even within the same country. These financial agreements generally may vary from country to country. As a result, for global roaming, knowledge of the country of operation can help the device to select the system offering the most favorable financial arrangement with the carrier.
By way of a more specific example, the carrier may operate its network over a wide geographic area, and the carrier will have roaming agreements with operators of other networks in many other areas where subscribers roam. In some countries, the carrier may operate a network and have a roaming agreement with another carrier for instances in which a mobile station can not obtain access to the carrier's own network. In such a case, it is preferable for the subscriber's mobile station to select the carrier's network first, select the network of the roaming partner second and select any other available network only in the event that the first two network choices are inaccessible. In other countries, the carrier may have agreements with two operators of local networks. However, in such a country, one roaming agreement offers better rates, therefore the network of the preferred roaming partner should be selected whenever possible.
Effective selection of networks of various operators under the various financial agreements are critical to the home network operator's profit margin, since when its customers roam, it wants to steer them to the roaming network that provides the best financial deal. When a user roams out of its home network operator's territory, either in country or out of country, its home network operator would naturally want the device to select the roaming network with which the home operator has the best financial deal. To achieve this, the home network operator's preference for which networks its customers use will vary from country to country.
The most efficient way in which the steering/selection to appropriate networks can be done automatically, is enabled if the device can determine the country in which it is operating, determine which networks are available in that area, look up one or more networks in a preference list of networks and then select the appropriate network that is available. It should be noted that the first step in such a preferential selection process involves a determination of the country of operation.
The need for the mobile station to determine the country in which the device is operating, however, is not limited only to automatic system selection by the device. An accurate country determination may also be helpful in different types of location based services. One example of a location based service or application relates to assisted dialing for international roaming. When a user travels from one country to another, the user needs to change (add or modify) the dial strings that are pre-fixed to the telephone number residing in a mobile station to match dialing protocol requirements for the country of current operations. For example, the International Direct Dial (IDD) prefix is 011 in the U.S.A., but the IDD is 00 in Venezuela. A U.S. number can be dialed from within the U.S. over a CDMA network without the IDD prefix. However, a U.S. number when dialed from Venezuela over a CDMA network would need to have the correct IDD prefix pre-pended to the telephone number when originating the call. To dial an international number from the USA, the user dials the 011 prefix followed by the international number. To make the same call from Venezuela, the user must dial the 00 prefix followed by the international number. This is not a problem when using the GSM/UMTS network since a “+” prefixed to the telephone number will result in the proper international call origination. Unfortunately, this is not the case for CDMA networks, as shown by the examples regarding the US and Venezuela. One solution would be to change how CDMA networks behave. This is usually problematic because network changes require more effort. An alternative might be to have the device implement an automatic program to determine the country from which the call is being originated and then pre-pend the appropriate IDD prefix to the dialed telephone number. However, again, this requires the device to determine the country of operation.
The need for the device to determine the country in which the device is operating is further exemplified in the following. Determination of country of operation might be used for web based applications running on the mobile station. As a specific example, suppose a user wanted to do a mobile station based web search of airports so that he could plan his out-going trip or local trip. If the device automatically knew the country location, then the search could be localized. An alternative would be for the application to ask the user to manually input the country information, which may be undesirable from the user viewpoint. Another alternative would be to change the network behavior so that this information is transmitted. In addition, in this case a network assisted solution requires device changes so that the device can properly read the information being sent by the network.
As outlined above, there are a variety of scenarios in which it is desirable to have the device know or determine the country in which it is currently operating, even as the user roams from country to country. User input of the information adds a user step that may not be convenient for the customer. Changes to network operations can be difficult to implement, particularly on a large scale. For example, it can be expensive and a difficult diplomatic issue to have carriers in various countries operating different iterations of various network technologies to all take steps to insure that their networks transmit a country identification in a standardized way. It may take considerable time for the appropriate standards bodies to agree and more time for the carriers to deploy upgraded equipment. Device changes so that the device can properly read the information being sent by the network, in accord with new international standards, also takes time and money to deploy widely to customers of many different service providers and may require customers to obtain updated mobile stations.
Hence a need exists for a technique to allow a mobile station to determine, detect, or identify the country in which it is currently operating from readily available information, without direct assistance from the local wireless communication network, for example, without requiring a new network broadcast of a country identification. It may also be desirable if the country determination solution did not require the device to support any particular wireless wide area network technology.